Difference between abstract class and interface

Answer Posted / cheshta

1. Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior.
2. Variables declared in a Java interface is by default final. An abstract class may contain non-final variables.
Members of a Java interface are public by default. A Java abstract class can have the usual flavors of class members like private, protected, etc..
3. Java interface should be implemented using keyword “implements”; A Java abstract class should be extended using keyword “extends”.
4. An interface can extend another Java interface only, an abstract class can extend another Java class and implement multiple Java interfaces.
5. A Java class can implement multiple interfaces but it can extend only one abstract class.
Interface is absolutely abstract and cannot be instantiated; 6. A Java abstract class also cannot be instantiated, but can be invoked if a main() exists.
7. In comparison with java abstract classes, java interfaces are slow as it requires extra indirection.

Is This Answer Correct ?    0 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

Explain the types of memory management? : Dot net architecture

498


How does an appdomain get created?

551


Explain Singleton design pattern in .net

574


Explain difference between state server and sqlserver? : .NET Architecture

531


What are public and private assemblies ?

528






What is gui programming? : .NET Architecture

503


Explain what does the term "green architecture" mean? : Dot net architecture

551


Explain the difference between primary & secondary storage device? : Dot net architecture

508


How do I know when my thread pool work item has completed?

498


What is .net transaction?

479


Explain difference between machine config vs. Web config? : .NET Architecture

538


what are the fundamental and common properties of .net controls?

1600


Explain about clr?

578


Explain .net mobile input controls? : Microsoft dot net mobile

482


What are the major differences between services and web services?

493